The present invention relates to a disk array apparatus.
A disk array apparatus having a plurality of storage devices has a volatile cache memory for increasing the speed of access from the host device. If power being supplied from an external power supply is shut OFF for such a reason as a power failure without executing power supply shut down processing in such a disk array apparatus, unwritten data in the cache memory is lost. To prevent this, a disk array apparatus according to Japanese Patent Application Laid-Open No. H9-330277 and No. 2005-165420, for example, has a battery as a backup power supply. In these disk array apparatuses, if a power failure occurs, power is supplied from the battery to the cache memory, saving the unwritten data in the cache memory to a nonvolatile storage device or the like.
If power supplied from the external power supply is shut OFF for such a reason as a power failure, the control board may be removed from the power supply unit for inspection. In such a case, electric shocks may occur if the power supply from the battery remains active.